I haven't used torrents for a very long time and saw this application mentioned on another forum.

From Wikipedia:

BitThief is a Java-based BitTorrent client designed to download from, but not upload to, BitTorrent networks. It is freeware and cross-platform. According to the BitThief homepage, it is intended as a proof of concept that there are weaknesses in the current BitTorrent protocol, which can be exploited by "cheating" BitTorrent clients (such as BitThief itself).